The present invention relates to a tapered roller bearing.
A tapered roller bearing which is used for supporting a pinion shaft in a differential gear of an automobile is lubricated by a large quantity of high-viscosity gear oil. For this reason, friction (dynamic friction) torque ascribable to rolling viscous resistance and the agitation resistance of oil is large, which constitutes one factor deteriorating the fuel consumption of the automobile. Accordingly, to promote further low fuel consumption, it is desirable to reduce the friction torque as practically as possible. To reduce the friction torque, it is known that it suffices if, for example, the number of tapered rollers is reduced, their length is shortened, or their diameter is made small. However, the reduction of the friction torque in such a manner leads to a substantial decline in the load carrying capacity as the bearing, so that it is not expedient to do so.